Shock-absorbing element for a motor vehicle

ABSTRACT

Known shock-absorbing elements are provided with overflow throttles equipped with sealing disks. These overflow throttles have different opening characteristics for the two directions which cannot be changed. The aim of the invention is therefore to provide a novel overflow throttle that can be freely selected and changed. To this end, the overflow throttle consists of a first ( 13 ) and a second overflow throttle ( 13 ) that are spatially separate and that are allocated to respective pressure chambers ( 10, 11 ). Both overflow throttles are provided with sealing disks ( 23 ) and are oriented opposite to the sense of the direction of flow. Every overflow throttle ( 13 ) is linked with the other pressure chamber ( 10, 11 ) via at least one through bore ( 35 ) that evades the opposite overflow throttle ( 13 ).

The Invention relates to a spring and damper unit according to thepreamble of claim 1.

Spring and damper units of this kind are predominantly employed in themotor vehicle technology.

Spring and damper units are known particular through the German printedpatent documents DE 3641623, DE 3824932, DE 4334007 and DE 8413300 U1.

In principle such a shock absorbing element comprises a cylindricalcasing with the cover and the double acting piston fitted into thecasing and having a one-sided piston rod penetrating the cover. Thecasing on the one hand and the piston rod on the other hand are solidlyconnected with a body part or, respectively, with the wheel suspension,wherein the free lying part of the piston rod is covered by bellows. Forthis purpose, the bellows are on the one hand attached to the cover ofthe casing and on the other hand attached to the head of the piston rod.

The piston subdivides the cylinder space of the casing into a pressurespace being reduced during compression and into a pressure space beingincreased during compression, wherein the two cylinder spaces areconnected to the outside through a casing connector to a source ofcompressed air and are connected to each other by one or severaloverflow throttles disposed in the piston.

For this purpose simple throttle bore holes are known from the Germanprinted patent document DE 36 41 623, wherein the simple throttle boreholes have the same throttle effect relative to the balancing air streamin both directions of motion, whereby the piston motion is damped to thesame extent in two directions. This is disadvantageous since a lesserdamping motion is desired during compression relative to the reboundbecause of the required ground adhesion.

An overflow throttle meeting such a requirement is shown in the Germanprinted patent document DE 84 13 300 U1, wherein the middle throttlebore whole on one side of the piston joins to a ring chamber on theother side of the piston and wherein the throttle bore hole is coveredfrom the ring chamber by a flexible ring disk. This ring disk has on theone hand an outer stop and on the other hand an inner stop such that thering disk lifts off from the respective stop in one flow passagedirection at the outer edge and in the other flow passage direction atthe inner edge. Different lever arms result from the different distanceof the two stops relative to the middle of the ring disk, wherein thetwo different lever arms effect a different opening characteristic forthe ring disk for the two passage flow directions. It is a disadvantagein connection with this usual kind of overflow throttles, that the ratioof the two opening characteristics with a onetime selected constructionis a fixed value and thereby not any longer changeable and adaptable tovarious application situations.

Spring and damper units are further known from the U.S. Pat. No.4,844,428, EP 0257779 A3, FR 2705127 A1 and EP 0671572 A1 which exhibittwo oppositely directed overflow throttles in the piston for the twopressure spaces. In particular the printed patent document EP 0671572 A1and the printed patent document FR 2705127 A1 show here overflowthrottles, which comprise several uniformly distributed and by sealingdisks in a direction closable passage bore holes.

These spring and damper units are complicated in construction and cantherefore be produced only with large expenditures. In addition, each ofthe two flow throttles has a special constructive form, wherebydifferent channel guides and dimensions result. This influences howeverthe opening characteristic of the overflow throttles and thereby thedamping behavior of the piston. Therefore these spring and damper unitscan only be employed for special cases of application.

Therefore it is an object of the present Invention to furnish a springand damper unit of the recited kind wherein the opening characteristicof the overflow throttle is freely selectable and changeable for eachpassage flow direction.

This object is achieved by the characterizing features of claim 1.Advantageous embodiments of the Invention result from the features ofclaims 2 through 7.

The Invention eliminates the recited disadvantages of thestate-of-the-art. The separate provision of the overflow throttle is aparticular functional advantage. The flow resistance at each overflowthrottle and thereby the damping characteristics for each direction ofmotion can be separately adjusted thereby by changing the sealing diskpackets. A functional dependency of the two overflow throttles does notexist. The spring and damper unit is thereby relatively simple and thuscost favorable in construction and in production.

The Invention is to be the explained in more detail in the following byway of several embodiments.

For this purpose there is shown in:

FIG. 1: a spring and damper unit in sectional view,

FIG. 2: the piston of the spring and damper unit in a first embodiment,

FIG. 3: a part section X of FIG. 2,

FIG. 4: the piston of the spring and damper unit in the secondembodiment, and

FIG. 5: the spring and damper unit with electromagnetic supportedsealing disks.

According to FIG. 1 the spring and damper unit comprises a cylindricalcasing 1 with a casing wall 2, a casing foot 3 for the mounting to awheel suspension over motor vehicle and a casing cover 4 disposedopposite to the casing foot 3. A piston 5 is fitted into conventionalway in the casing 1, wherein the piston 5 exhibits a piston rod 6 on oneside. This piston rod 6 penetrates the casing cover 4 and is equipped atthe free end of the piston rod 6 with a piston rod head 7, wherein thepiston rod head 7 is furnished for stopping at the body of the motorvehicle. The part of the piston rod 6 protruding from the casing 5penetrates a pressure chamber, wherein the pressure chamber issurrounded by the bellows 8 in the kind that the bellows 8 is attachedat the casing cover 4 on the one hand and at the piston rod head 7 onthe other hand. The piston 5 is furnished sealingly relative to thecylinder wall 2 with a piston ring 9 and thus divides the availableinner space of the casing 1 into a first pressure space 10 and into asecond pressure space 11. The second pressure space 11 is connected tothe pressure chamber surrounded by the bellows 8 through a bore holedisposed in the piston rod 6. One of the two pressure spaces 10, 11 isconnected to a source of compressed air through a compressed airconnector 12, wherein the source of compressed air generates a desiredpressure in the two pressure chambers 10, 11 and maintains the desiredpressure at a constant value. The overflow throttle 13 is disposed inthe piston 5, wherein the overflow throttle 13 connects the two pressurespaces 10 and 11 to each other and wherein a volume stream balancing ofthe enclosed compressed air is performed by a corresponding motion ofthe piston over the two pressure spaces 10 and 11.

Such an overflow throttle 13 according to a first form is constructedaccording to FIGS. 2 and 3 such that the piston 5 has a pot shaped formwith a hollow space 14, which hollow space 14 is disposed with its openside toward the casing foot 3. The closed front face of the piston 5disposed on the side of the piston rod is equipped with several axialflow through bore holes 15 uniformly distributed over a partial circle.

A throttle insert 16 is disposed in the hollow space 14 of the piston 5,wherein the throttle insert 16 carries a sealing element 17 at thejacket face of the throttle insert 16 and thereby seals the throttleinsert 16 relative to the hollow space 14 of the piston. This throttleinsert 16 is constructed of several parts and comprises a first coverpiece 18 disposed inside in the hollow space 14, a second cover piece 19disposed on the outside as well as an intermediately disposed middlepiece 20, wherein the first cover piece 18, the middle piece 20, and thesecond cover piece 19 are screwed together and art jointly attached atthe piston 5 with screws 21. The first cover piece 18 is equipped with aradially acting sealing element 22, which sealing element 22 closes theintermediate space between the throttle insert 16 and the closed frontface of the piston 5. In each case one or several sealing disks 23 andspacer disks 24 are disposed between the first cover piece 18 and themiddle piece 20 as well as between the middle piece 20 and the secondcover piece 19 and are jointly tensioned and clamped with the throttleinsert 16.

Several throttle channels are furnished in axially parallel extension inthe throttle insert 16, wherein the throttle channels 15 connect orclose the first pressure space 10 and the second pressure space 11 inconnection and in cooperation with the axial flow through bore holes 15and the sealing disks 23. Initially the first cover piece 18 isfurnished with the several axial parallel aligned and uniformlydistributed on a part circle disposed passage bore holes 25, whichpassage bore holes 25 are connected to passage bore holes 15 in thepiston 5 continuously on the one hand through a not illustrated ringchannel in the piston 5 or in the first cover piece 18. On the otherhand the passage bore holes 25 of the first cover piece 18 join into acirculating ring groove 26, wherein the circulating ring groove 26 isfurnished in cross-section toward the axis with the conical stop face 27for the sealing disks 23. An internal web face 28 as well as an outerweb face 29 are disposed at the two sides of the ring groove 26.

The second cover piece 19 is furnished just as in the cover piece 18with formed and disposed passage bore holes 30, wherein the passage boreholes 30 join into an equally form ring groove 31 on the piston rod sidewith a conical stop face 32 for the sealing disks 23. An inner web face33 and the outer web face 34 again result through the ring groove 31.

The middle piece 20 disposed between the two cover pieces 18 and 19 isequipped with further passage bore holes 35, wherein the passage boreholes 35 are disposed uniformly distributed and are formed as inclinedbore holes. Here the passage bore holes 35 run alternately, such as isshown in FIG. 2, from a larger part circle diameter of a first side to asmaller part circle diameter of the second side and the neighboringpassage bore holes 35 oppositely from a smaller part circle diameter ofthe first side to a larger part circle diameter of the second side. Aninner row and an outer row of openings of the passage bore holes 35thereby result at the two sides of the middle piece 20, wherein thepassage bore holes 35 in each case are combined by an inner ring groove36 and by an outer ring groove 37 on the first side and by an inner ringgroove 38 and by an outer ring groove 39 on the second side. In eachcase there result an inner web face 40, a middle web face 41, and anouter wet face 42 by the two neighboring ring groove 36, 37 or,respectively 38, 39 on each side.

One or several sealing disks 23 are disposed in the mounted statebetween the first cover piece 18 and the middle piece 20 as well asbetween the second cover piece 19 and the middle piece 20 in such waythat the inner disposed region of the sealing disks 23 is solidlyclamped between the inner web face 28 of the first cover piece 18 andthe inner web face 40 of the middle piece 20 and wherein the outerregion of the sealing disk 23 comes to rest on the middle web face 41 ofthe middle piece 20. The spacer disks 24 have the same or a lesserstrength as compared to the sealing disks 23 and are clamped between theouter web faces 29 of the first cover piece 18 and the outer web faces42 of the middle piece 20.

The sealing disks 23 between the second cover piece 19 and the middlepiece 20 are clamped between the two oppositely disposed web faces 33and 40 in the same way and are brought to rest on the middle web face 41of the middle piece 20. A selected pretension can be applied to thesealing disks 23, wherein the oppositely disposed inner web faces 28, 33of the two cover pieces 18, 19 obtained a longer radial distance fromthe middle axis as compared to the way of providing the inner web faces40 at the two sides of the middle piece 20. A selected pretension at thesealing disks 23 can also be generated by having the spacer disks 24 asmaller thickness as compared to the sealing disks 23.

It is also possible to obtain a pretension of the sealing disks 23,where usual spring disks are employed instead of the sealing disks 23.Then an unequal radial distance to the middle axis of the web faces 28,33 and 40 and/or a smaller thickness of the spacer disks 24 can bedispensed with.

Compressed air subjected to pressure in the pressure space 11 forexample flows through all passage bore holes 30 into the ring groove 31of the second cover piece 19 based on the motion of the piston. Here thecompressed air loads the sealing disks 23 and closes the inner ringgroove 38 of the front side of the middle piece 20. Therewith theconnection to each second passage bore hole 35 is interrupted. Thecompressed air flows however through the outer ring groove 39 to eachother second passage bore hole 35 and passes into the inner ring groove36 of the rearside of the middle piece 20 and charges the sealing disk23 for such time until a required pressure has set in for lifting offthe sealing disks 23. Here only the outer edge of the sealing disks 23lifts off from the middle web face 41 of the middle piece 20 and becomesto rest at the conical stop face 27 of the first cover piece 18. Thecompressed air flows through the passage bore holes 25 or, respectively,15 of the first cover piece 18 or, respectively, of the piston 5 intothe pressure space 10 through the open sealing disks 23.

The compressed air flows in the same way in reverse direction of motionof the piston 5 however through the other passage bore holes 35 in themiddle piece 20 from the pressure space 10 into the pressure space 11.Thus the compressed air stream retains closed the sealing disks 23disposed next in flow direction in each second passage bore hole 35 ofthe middle piece 20 and opens and passes through the remotely disposedsealing disks 23.

A second embodiment of the flow-through throttle 13 comprises a piston5′ according to FIG. 4, wherein the piston 5′ is clamped in axialdirection on the piston rod 6′ between a pretension piston clamping ring43 and a fixedly disposed piston clamping ring 44, and wherein thepiston 5′ separates the two pressure spaces 10′, 11′ in a conventionalway from each other. The two piston clamping rings 43, 44 have conicalstop faces 45 and 46 formed in a special way on the front faces disposedtoward each other for the ring disks 23, as well as in each case a webface 47 and 48 following in the direction of the axis of the piston rod6′. The piston 5′ has in each case a ring groove 49 on the one hand anda ring groove 50 on the other hand at the two front faces. Here in eachcase one of the ring grooves 49, 50 is connected to the oppositelydisposed pressure space 10′, 11′ through several inclined runningpassage bore holes 51 and are under bypassing of the oppositely disposedring groove 49, 50. All passage bore holes 51 are disposed on the samepart circle and are arranged uniformly distributed on this part circle.

The two ring grooves 49, 50 are covered sealingly by the sealing disks23, wherein the sealing disks 23 in each case are tensed in the regionclose to the axis by the web faces 47 and 48 of the two piston clampingrings 43 and 44 and by oppositely disposed web faces 52 and 53 at thepiston 5′ and wherein the web faces 47 and 48 come to rest in the regionremote to the axis body in each case are web face 54 and 55 of thepiston 5′.

Again the sealing disks 23 can be employed individually or in packets. Apretension subjecting the sealing disks 23 can be generated by acorresponding selection of the radial distances of the web faces 47, 48clamping the sealing disks 23′ at the piston clamping rings 43, 44 andat the web faces 52 and 53 at the piston 5′ and in connection with thefurnished clamping force between the two piston clamping rings 43, 44.

The second embodiment is equipped in each case with the packets of atleast two sealing disks 23 according to FIG. 5. The sealing disks 23here comprise a magnetizable material. In addition each packet ofsealing disks 23 is coordinated to an electromagnet 56 and 57, whereinthe electromagnet 56 and 57 in each case encloses the piston 5′ and eachrecord of sealing disks 23 separately in an externally controllablemagnet flux move. The magnet flux here changes the tensions of thepackets of sealing disks 23 and influences thereby the openingcharacteristics all the sealing disks 23 in a tuned way relative to aconcrete application case.

List of Reference Numerals

1 casing

2 casing wall

3 casing foot

4 casing cover

5,5′ piston

6,6′ piston rod

7 piston rod head

8 bellows

9 piston ring

10, 10′ first pressure space

11, 11′ second pressure space

12 compressed air supply

13 overflow throttle

14 hollow space

15 flow-through bore hole

16 throttle insert

17 sealing elements

18 first cover piece

19 second cover piece

20 middle piece

21 screw

22 sealing element

23 sealing disks

24 spacer disk

25 passage bore hole

26 ring groove

27 conical stop face

28 inner web face

29 outer web face

30 passage bore hole

31 ring groove

32 conical stop face

33 inner web face

34 outer web face

35 passage bore hole

36 inner ring groove

37 outer ring groove

38 inner ring groove

39 outer ring groove

40 inner web face

41 middle web face

42 outer web face

43 pretensioned piston clamping ring

44 fixed piston clamping ring

45 conical stop face

46 conical stop face

47 web face

48 web face

49 ring groove

50 ring groove

51 passage bore hole

52 web face

53 web face

54 web face

55 web face

56 electromagnet

57 electromagnet

What is claimed is:
 1. A spring and damper unit for a motor vehiclecomprising a cylindrical casing (1) forming a cylinder chamber andfilled with compressed air; a double acting piston (5,5′) having aone-sided piston rod (6,6′), wherein the cylindrical casing (1) and thepiston rod (6,6′) are adapted for being clamped between a body part anda wheel of the motor vehicle and wherein the double acting piston (5,5′)divides the cylinder chamber of the casing (1) into two pressurechambers (10, 10′, 11, 11′); a first overflow throttle (13) connectingthe two pressure chambers (10, 10′, 11, 11′) to each other in the doubleacting piston (5,5) for the purpose of volume balancing wherein thefirst overflow throttle (13) includes a first passage and a firstspringing sealing disk (23) for opening or closing the first passage; asecond overflow throttle (13) connecting the two pressure chambers (10,10′, 11, 11′) to each other in the double acting piston (5,5) for thepurpose of volume balancing, wherein the second overflow throttle (13)includes a second passage and a second springing sealing disk (23) foropening or closing the second passage, wherein the first overflowthrottle (13) is disposed oppositely directed relative to the secondoverflow throttle (13) with respect to a flow passage direction andwherein a blocked first overflow throttle (13) can be bypassed by a freesecond overflow throttle (13); a first plurality of passage bore holes(35, 51) are coordinated to the first overflow throttle (13); a secondplurality of passage bore holes (35, 51) are coordinated to the secondoverflow throttle (13); wherein first smaller part openings of the firstplurality of passage bore holes (35, 51) of a first smaller part circleand first larger part openings of the first plurality of passage boreholes (35, 51) of a first larger part circle of each side are separatedfrom each other by a first ring shaped web face (41, 54), and whereinthe first springingly sealing disks (23) with their large diameterregion are sealingly resting on the first ring-shaped web face (41,54);and wherein second smaller part openings of the second plurality ofpassage bore holes (35, 51) of a second smaller part circle and secondlarger part openings of the second plurality of passage bore holes (35,51) of a second larger part circle of each side are separated from eachother by a second ring shaped web face (41, 54), and wherein the secondspringingly sealing disks (23) with their large diameter region aresealingly resting on the second ring-shaped web face (41,54).
 2. Thespring and damper unit according to claim 1 further comprising firstcover pieces (18, 19) contacting and tensioning the first springinglysealing disks (23) against the front faces of the piece (5, 5′); andconical stop faces (27, 32, 45, 46) are formed at the first cover pieces(18, 19).
 3. The spring and damper unit according to claim 1 wherein thefirst springingly sealing disks (23) and the second springingly sealingdisks are pretensioned into their closing position by a different radialdistance of the inner web faces (28, 33) of the cover pieces (18, 19)relative to the inner web faces (40) of the middle piece (20) or theaxis of the piston (6) and/or by a lower thickness of the spacer disks(24) relative to the thickness of the sealing disks (23).
 4. The springand damper unit according to claim 1 wherein the first springinglysealing disks (23) and the second springingly sealing disks arepretensioned into their closing position by a different radial distanceof the inner web faces (28, 33) of the cover pieces (18, 19) relative tothe inner web faces (40) of the middle piece (20) or the axis of thepiston (6).
 5. The spring and damper unit according to claim 1 whereinthe first springingly sealing disks (23) and the second springinglysealing disks are pretensioned into their closing position by a lowerthickness of the spacer disks (24) relative to the thickness of thesealing disks (23).
 6. The spring and damper unit according to claim 1further comprising a throttle insert (16); a first cover piece (18); asecond cover piece (19); a middle piece (20); a first spacer disk (24)disposed between the first cover piece (18) and the middle piece (20); asecond spacer disk (24) disposed between the middle piece (20) and thesecond cover piece (19), wherein the first spacer disk (24) and thesecond spacer disk (24) are jointly tensioned and clamped with thethrottle insert (16).
 7. The spring and damper unit according to claim 1further comprising a first cover piece (18); first passage bore holes(25) disposed in the first cover piece (18); a first circulating ringgroove (26) disposed in the first cover piece (18), wherein the firstpassage bore holes (25) disposed in the first cover piece (18) join intothe first circulating ring groove (26), a first conical stop face (27)for the first springingly sealing disks (23) and disposed in the firstcover piece, wherein the first circulating ring groove (26) is joinedtoward an axis of the cylindrical casing (1) by the first conical stopface (27).
 8. The spring and damper unit according to claim 7 furthercomprising a second cover piece (19); second passage bore holes (30)disposed in the second cover piece (19); a second circulating ringgroove (31) disposed in the second cover piece (19), wherein the secondpassage bore holes (30) disposed in the second cover piece (19) joininto the second circulating ring groove (31), a second conical stop face(32) for the second springingly sealing disks (23) and disposed in thesecond cover piece, wherein the second circulating ring groove (31) isjoined toward the axis by the second conical stop face (32).
 9. A springand damper unit for a motor vehicle comprising a cylindrical casing (1)forming a cylinder chamber and filled with compressed air; a doubleacting piston (5,5′) having a one-sided piston rod (6,6′), wherein thecylindrical casing (1) and the piston rod (6,6′) are adapted for beingclamped between a body part and a wheel of the motor vehicle and whereinthe double acting piston (5,5′) divides the cylinder chamber of thecasing (1) into two pressure chambers (10, 10′, 11, 11′); a firstoverflow throttle (13) connecting the two pressure chambers (10, 10′,11, 11′) to each other in the double acting piston (5,5) for the purposeof volume balancing wherein the first overflow throttle (13) includes afirst passage and a first springing sealing disk (23) for opening orclosing the first passage; a second overflow throttle (13) connectingthe two pressure chambers (10, 10′, 11, 11′) to each other in the doubleacting piston (5,5) for the purpose of volume balancing, wherein thesecond overflow throttle (13) includes a second passage and a secondspringing sealing disk (23) for opening or closing the second passage,wherein the first overflow throttle (13) is disposed oppositely directedrelative to the second overflow throttle (13) with respect to a flowpassage direction and wherein a blocked first overflow throttle (13) canbe bypassed by a free second overflow throttle (13); a first pluralityof passage bore holes (35, 51) are coordinated to the first overflowthrottle (13), wherein the first plurality of passage bore holes (35,51) is disposed on a first common part circle in a uniform distribution,wherein the first plurality of passage bore holes (35, 51) of the firstoverflow throttle (13) is formed as a first plurality of inclined boreholes and are running alternately from a first larger part circle on theone hand to a first smaller part circle on the other hand; a secondplurality of passage bore holes (35, 51) are coordinated to the secondoverflow throttle (13), wherein the second plurality of passage boreholes (35, 51) is disposed on a second common part circle in a uniformdistribution, wherein the second plurality of passage bore holes (35,51) of the second overflow throttle (13) is formed as a second pluralityof inclined bore holes and are running alternately from a second largerpart circle on the one hand to a second smaller part circle on the otherhand; wherein first smaller part openings of the first plurality ofpassage bore holes (35, 51) of the first smaller part circle and firstlarger part openings of the first plurality of passage bore holes (35,51) of the first larger part circle of each side are separated from eachother by a first ring shaped web face (41, 54), and wherein the firstspringingly sealing disks (23) with their large diameter region aresealingly resting on the first ring-shaped web face (41,54); and whereinsecond smaller part openings of the second plurality of passage boreholes (35, 51) of the second smaller part circle and second larger partopenings of the second plurality of passage bore holes (35, 51) of thesecond larger part circle of each side are separated from each other bya second ring shaped web face (41, 54), and wherein the secondspringingly sealing disks (23) with their large diameter region aresealingly resting on the second ring-shaped web face (41,54).
 10. Thespring and damper unit according to claim 9 wherein the first passagebore holes (35, 51) of the first overflow throttle (13) join on a firstside of the piston (5, 5′) into a ring groove (36, 38, 49, 50); andwherein the first over flow throttle (13) and the second overflowthrottle (13) are disposed at the same radial distance from the middleaxis and wherein the second passage bore holes (35, 51) of the secondoverflow throttle (13) join on a second side of the piston (5, 5′) intoa ring groove (36, 38, 49, 50).
 11. The spring and damper unit accordingto claim 9 wherein the first springingly sealing disks (23) of the firstoverflow throttle (13) are made of a spring material and are fixedlyclamped in the region of their smaller diameter; wherein secondspringingly sealing disks (23) of the second overflow throttle (13) aremade of a spring material and are fixedly clamped in the region of theirsmaller diameter.
 12. The spring and damper unit according to claim 11further comprising first cover pieces (18, 19) tensioning the firstspringingly sealing disks (23) against the front faces of the piece (5,5′); and conical stop faces (27, 32, 45, 46) are formed at the firstcover pieces (18, 19).
 13. The spring and damper unit according to claim12 further comprising a first electromagnet (56, 57) coordinated to thefirst overflow throttle (13); a second electromagnet (56, 57)coordinated to the second overflow throttle (13).
 14. The spring anddamper unit according to claim 11 further comprising first cover pieces(18, 19) tensioning the first springingly sealing disks (23) by pistonclamping rings (43,44) against the front faces of the piece (5, 5′); andconical stop faces (27, 32, 45, 46) formed at the piston clamping rings(43, 44).
 15. The spring and damper unit according to claim 11 whereinthe first springingly sealing disks (23) and the second springinglysealing disks are pretensioned into their closing position by adifferent radial distance of the inner web faces (28, 33) of the coverpieces (18, 19) relative to the inner web faces (40) of the middle piece(20) or the axis of the piston (6) and/or by a lower thickness of thespacer disks (24) relative to the thickness of the sealing disks (23).16. The spring and damper unit according to claim 11 further comprisinga first electromagnet (56, 57) coordinated to the first overflowthrottle (13); a second electromagnet (56, 57) coordinated to the secondoverflow throttle (13).
 17. The spring and damper unit according toclaim 11 wherein the first springingly sealing disks (23) and the secondspringingly sealing disks are pretensioned into their closing positionby a different radial distance of the inner web faces (28, 33) of thecover pieces (18, 19) relative to the inner web faces (40) of the middlepiece (20) or the axis of the piston (6).
 18. Spring and damper unit formotor vehicle comprising a cylindrical casing (1) filled with compressedair and a double acting piston (5,5′) with a one-sided piston rod(6,6′), wherein the casing (1) and the piston rod (6,6′) are clampedbetween a body part and a wheel of the motor vehicle and wherein thepiston (5,5′) divides the cylinder space of the casing (1) into twopressure spaces (10, 10′, 11, 11′) and wherein the two pressure spaces(10, 10′, 11, 11′) are connected to each other through a first overflowthrottle (13) and through a second overflow throttle (13) in the piston(5,5′) for the purpose of volume balancing wherein each said overflowthrottle (13) comprises a passage and a plurality of springing sealingdisks (23) for opening or closing the passage, wherein one of theplurality of springing sealing disks (23) is disposed oppositelydirected relative to another one of the plurality of springing sealingdisks (23) in their flow passage direction and wherein a blocked one ofthe overflow throttles (13) can be bypassed by a free remaining one ofthe overflow throttles (13), wherein several passage bore holes (35, 51)are coordinated to each overflow throttle (13), wherein the passage boreholes (35, 51) are disposed on a common part circle in uniformdistribution, the passage bore holes (35, 51) of the two overflowthrottles (13) are formed as inclined bore holes and are runningalternately from a larger part circle on the one hand to a smaller partcircle on the other hand, the openings of the passage bore holes (35,51) of the smaller part circle and the openings of the passage boreholes (35, 51) of the larger part circle of each side are separated fromeach other by a ring shaped web face (41, 54), and the sealing disks(23) having a large diameter region are sealingly resting on the webfaces (41,54).
 19. Spring and damper unit according to claim 10characterized in that the sealing disks (23) of each overflow throttle(13) are made of a spring material and are fixedly clamped in the regionof their smaller diameter.
 20. Spring and damper unit according to claim19, characterized in that an electromagnet (56, 57) is coordinated toeach overflow throttle (13).
 21. Spring and damper unit according toclaim 19 characterized in that the sealing disks (23) are tensioned bycover pieces (18, 19) or by piston clamping rings (43,44) against thefront faces of the piece (5, 5′) and that conical stop faces (27, 32,45, 46) are formed at the cover pieces (18, 19) or at the pistonclamping rings (43, 44).
 22. Spring and damper unit according to claim18 characterized in that the two over flow throttles (13) are disposedat the same radial distance from the middle axis and the passage boreholes (35, 51) of the overflow throttles (13) join on each side of thepiston (5, 5′) into a ring groove (36, 38, 49, 50).
 23. The spring anddamper unit according to claim 18 further comprising one or severalspacer disks (24) disposed between a first cover piece (18) and a middlepiece (20) as well as between the middle piece (20) and a second coverpiece (19) together with the sealing disks (23) and are jointlytensioned and clamped with a throttle insert (16), wherein the spacerdisks (24) have the same or a lesser strength and a larger diameter ascompared to the sealing disks (23) and wherein the spacer disks (24) areclamped between outer web faces (29) of the first cover piece (18) andouter web faces (42) of the middle piece (20) as well as between outerweb faces (34) of the second cover piece (19) and the outer web faces(42) of the middle piece (20).
 24. The spring and damper unit accordingto claim 23 wherein the spacer disks (24) are concentric cylindricaldisks disposed on the same level in axial direction as the sealing disks(23), and wherein an outer diameter of the spacer disks (24) issubstantially the same as an outer diameter of the first cover piece(18), of the second cover piece (19) and of the middle piece (20), andwherein an inner diameter of the spacer disks (24) is larger than anouter diameter of the sealing disks (23).
 25. Spring and damper unit formotor vehicle comprising a cylindrical casing (1) filled with compressedair and a double acting piston (5,5′) with a one-sided piston rod(6,6′), wherein the casing (1) and the piston rod (6,6′) are clampedbetween a body part and a wheel of the motor vehicle and wherein thepiston (5,5′) divides the cylinder space of the casing (1) into twopressure spaces (10, 10′, 11, 11′) and wherein the two pressure spaces(10, 10′, 11, 11′) are connected to each other through a first overflowthrottle (13) and through a second overflow throttle (13) in the piston(5,5′) for the purpose of volume balancing wherein each said overflowthrottle (13) comprises a passage and a plurality of springing sealingdisks (23) for opening or closing the passage, wherein one of theplurality of springing sealing disks (23) is disposed oppositelydirected relative to another one of the plurality of springing sealingdisks (23) in their flow passage direction and wherein a blocked one ofthe overflow throttles (13) can be bypassed by a free remaining one ofthe overflow throttles (13), wherein several passage bore holes (35, 51)are coordinated to each overflow throttle (13), wherein the passage boreholes (35, 51) are disposed on a common part circle in uniformdistribution, the passage bore holes (35, 51) of the two overflowthrottles (13) are formed as inclined bore holes and are runningalternately from a larger part circle on the one hand to a smaller partcircle on the other hand, the openings of the passage bore holes (35,51) of the smaller part circle and the openings of the passage boreholes (35, 51) of the larger part circle of each side are separated fromeach other by a ring shaped web face (41, 54), and the sealing disks(23) having a large diameter region are sealingly resting on the webfaces (41, 54), wherein the sealing disks (23) are pretensioned intotheir closing position, by a different radial distance of the inner webfaces (28, 33) of the cover pieces (18, 19) relative to the inner webfaces (40) of the middle piece (20) or the axis of the piston (6) and/orby a lower thickness of the spacer disks (24) relative to the thicknessof the sealing disks (23).
 26. A spring and damper unit for a motorvehicle comprising a cylindrical casing (1) forming a cylinder chamberand filled with compressed air; a double acting piston (5,5′) having aone-sided piston rod (6,6′), wherein the cylindrical casing (1) and thepiston rod (6,6′) are adapted for being clamped between a body part anda wheel of the motor vehicle and wherein the double acting piston (5,5′)divides the cylinder chamber of the casing (1) into two pressurechambers (10, 10′, 11, 11′); a first overflow throttle (13) connectingthe two pressure chambers (10, 10′, 11, 11′) to each other in the doubleacting piston (5,5) for the purpose of volume balancing wherein thefirst overflow throttle (13) includes a first passage and a firstspringing sealing disk (23) for opening or closing the first passage; asecond overflow throttle (13) connecting the two pressure chambers (10,10′, 11, 11′) to each other in the double acting piston (5,5) for thepurpose of volume balancing, wherein the second overflow throttle (13)includes a second passage and a second springing sealing disk (23) foropening or closing the second passage, wherein the first overflowthrottle (13) is disposed oppositely directed relative to the secondoverflow throttle (13) with respect to a flow passage direction andwherein a blocked first overflow throttle (13) can be bypassed by a freesecond overflow throttle (13); a first plurality of passage bore holes(35, 51) are coordinated to the first overflow throttle (13), whereinthe first plurality of passage bore holes (35, 51) is disposed on afirst common part circle in a uniform distribution, wherein the firstplurality of passage bore holes (35, 51) of the first overflow throttle(13) is formed as a first plurality of inclined bore holes and arerunning alternately from a first larger part circle on the one hand to afirst smaller part circle on the other hand; a second plurality ofpassage bore holes (35, 51) are coordinated to the second overflowthrottle (13), wherein the second plurality of passage bore holes (35,51) is disposed on a second common part circle in a uniformdistribution, wherein the second plurality of passage bore holes (35,51) of the second overflow throttle (13) is formed as a second pluralityof inclined bore holes and are running alternately from a second largerpart circle on the one hand to a second smaller part circle on the otherhand; wherein first smaller part openings of the first plurality ofpassage bore holes (35, 51) of the first smaller part circle and firstlarger part openings of the first plurality of passage bore holes (35,51) of the first larger part circle of each side are separated from eachother be a first ring shaped web face (41, 54), and wherein the firstspringingly sealing disks (23) with their large diameter region aresealingly resting on the first ring-shaped web face (41,54); and whereinsecond smaller part openings of the second plurality of passage boreholes (35, 51) of the second smaller part circle and second larger partopenings of the second plurality of passage bore holes (35, 51) of thesecond larger part circle of each side are separated from each other bya second ring shaped web face (41, 54), and wherein the secondspringingly sealing disks (23) with their large diameter region aresealingly resting on the second ring-shaped web face (41,54), whereinthe first springingly sealing disks (23) of the first overflow throttle(13) are made of a spring material and are fixedly clamped in the regionof their smaller diameter; wherein second springingly sealing disks (23)of the second overflow throttle (13) are made of a spring material andare fixedly clamped in the region of their smaller diameter, wherein thefirst springingly sealing disks (23) and the second springingly sealingdisks are pretensioned into their closing position by a lower thicknessof the spacer disks (24) relative to the thickness of the sealing disks(23).
 27. The spring and damper unit for a motor vehicle comprising acylindrical casing (1) forming a cylinder chamber and filled withcompressed air; a double acting piston (5,5′) having a one-sided pistonrod (6,6′), wherein the cylindrical casing (1) and the piston rod (6,6′)are adapted for being clamped between a body part and a wheel of themotor vehicle and wherein the double acting piston (5,5′) divides thecylinder chamber of the casing (1) into two pressure chambers (10, 10′,11, 11′); a first overflow throttle (13) connecting the two pressurechambers (10, 10′, 11, 11′) to each other in the double acting piston(5,5) for the purpose of volume balancing wherein the first overflowthrottle (13) includes a first passage and a first springing sealingdisk (23) for opening or closing the first passage; a second overflowthrottle (13) connecting the two pressure chambers (10, 10′, 11, 11′) toeach other in the double acting piston (5,5) for the purpose of volumebalancing, wherein the second overflow throttle (13) includes a secondpassage and a second springing sealing disk (23) for opening or closingthe second passage, wherein the first overflow throttle (13) is disposedoppositely directed relative to the second overflow throttle (13) withrespect to a flow passage direction and wherein a blocked first overflowthrottle (13) can be bypassed by a free second overflow throttle (13); afirst plurality of passage bore holes (35, 51) are coordinated to thefirst overflow throttle (13), wherein the first plurality of passagebore holes (35, 51) is disposed on a first common part circle in auniform distribution, wherein the first plurality of passage bore holes(35, 51) of the first overflow throttle (13) is formed as a firstplurality of inclined bore holes and are running alternately from afirst larger part circle on the one hand to a first smaller part circleon the other hand; a second plurality of passage bore holes (35, 51) arecoordinated to the second overflow throttle (13), wherein the secondplurality of passage bore holes (35, 51) is disposed on a second commonpart circle in a uniform distribution, wherein the second plurality ofpassage bore holes (35, 51) of the second overflow throttle (13) isformed as a second plurality of inclined bore holes and are runningalternately from a second larger part circle on the one hand to a secondsmaller part circle on the other hand; wherein first smaller partopenings of the first plurality of passage bore holes (35, 51) of thefirst smaller part circle and first larger part openings of the firstplurality of passage bore holes (35, 51) of the first larger part circleof each side are separated from each other by a first ring shaped webface (41, 54), and wherein the first springingly sealing disks (23) withtheir large diameter region are sealingly resting on the firstring-shaped web face (41,54); and wherein second smaller part openingsof the second plurality of passage bore holes (35, 51) of the secondsmaller part circle and second larger part openings of the secondplurality of passage bore holes (35, 51) of the second larger partcircle of each side are separated from each other by a second ringshaped web face (41, 54), and wherein the second springingly sealingdisks (23) with their large diameter region are sealingly resting on thesecond ring-shaped web face (41,54); a throttle insert (16); a firstcover piece (18); a second cover piece (19); a middle piece (20); afirst spacer disk (24) disposed between the first cover piece (18) andthe middle piece (20); a second spacer disk (24) disposed between themiddle piece (20) and the second cover piece (19), wherein the firstspacer disk (24) and the second spacer disk (24) are jointly tensionedand clamped with the throttle insert (16).
 28. The spring and damperunit according to claim 27 wherein the first spacer disk (24) and thesecond spacer disk (24) have a same or a lesser strength and a largerdiameter as compared to the first springing sealing disk (23) and thesecond springing sealing disk (23) and wherein the first spacer disk(24) is clamped between outer web faces (29) of the first cover piece(18) and first outer web faces (42) of the middle piece (20) and whereinthe second spacer disk (24) is clamped between outer web faces (34) ofthe second cover piece (19) and second outer web faces (42) of themiddle piece (20).